//
// Created by madison on 2022/1/6.
//

#include <iostream>

using namespace std;

// 变量声明
extern int a, b;
extern int c;
extern float f;

int main() {
    // 变量定义
    int a, b;
    int c;
    float f;

    // 实际初始化
    a = 10;
    b = 20;
    c = a + b;

    cout << c << endl;

    f = 70.0 / 3.0;
    cout << f << endl;
    return 0;
}